Technical Abstract:
During the past 125 years the northern Chihuahuan Desert has undergone a significant shift from desert grasslands to desert scrub conditions, with mesquite (Prosopis glandulosa) dramatically increasing in dominance during this period. The transition from desert grasslands is viewed as deleterious, decreasing forage availability for both wildlife and livestock while negatively impacting air, water, and soil processes that support ecosystem services important to rapidly growing, human populations. Causes leading to this transition include formulation of government and industry policies, and later application of some range management principles, without an understanding of the evolutionary and landscape history of the northern Chihuahuan Desert. In addition, as causes of mesquite expansion were determined, primary factors leading to mesquite’s eventual dominance did not receive adequate attention, most likely because they did not fit within dominant scientific paradigms, or social-political realities of the time. Future work needs to focus on better understanding evolutionary and landscape legacies of this region; including factors that created and maintained the original desert grasslands prior to desert scrub conditions. Using this understanding we must create appropriate theory that will guide future human-ecological interactions and assessment of ecological trajectories. This knowledge must affect policy and eventual management. We must relax the need for ecosystems to adapt to human behaviors and consider how human behaviors can best adapt to the ecosystems on which they depend.